This invention relates generally to single or multipole circuit breakers and transfer switches, and more particularly to stored energy circuit breakers and transfer switches.
The basic functions of these devices are to provide separable electrical contact switching to make or break electrical connections in circuits. Circuit breakers are typically designed to detect abnormal conditions in circuits and make or break electrical connections in response to those conditions. Circuit breakers also usually may be switched on or off manually. Transfer switches have a similar function in switching electrical connections in response to manual or signal inputs or predetermined electrical conditions.
The operating voltage, continuous current, frequency, short circuit interrupting capability, and time-current coordination needed are some of the factors which must be considered when designing one of these devices. Government and market requirements are placing increasing demands upon the electrical industry for breakers and switches with improved performance in smaller packages and with numerous new and novel features.
Stored energy mechanisms for use in circuit breakers and transfer switches of the single pole or multi-pole type are known in the art- A particular construction of such mechanisms is primarily dependent upon a parameter such as the rating of the breaker. A variety of mechanical arrangements are known which utilize mechanical energy stored in a biasing device such as a spring. The stored mechanical energy is used to provide the mechanical force necessary to drive a latch and trip mechanism which opens and closes separable contacts, which function to make or break electrical connections in the circuit.
Such a device also necessarily includes means for charging the spring--storing mechanical energy to be released later in operation of the device. Such means have included electric motor-driven charging mechanisms as well as manually-operated charging mechanisms, or both.
One type of circuit breaker design utilizes mechanical linkages coupled to a rotating shaft to charge a spring. An example of this type can be seen in U.S. Pat. No. 4,404,446 issued Sept. 13, 1983 to Maier et al. This design comprises a rotating charging shaft which exits the latch and trip mechanism of the breaker, rotation of the shaft by an applied force being the means by which the spring of the breaker is charged.
This shaft must be rotated by a mechanism which prevents rotation in the reverse direction, i.e., which allows rotation in only one direction. This "locking" is necessary to prevent loss of stored mechanical energy through rotation of the shaft in a direction opposite the charging direction--to prevent the spring from discharging.
Prior to the invention disclosed herein, the means used to supply the rotational charging force and locking function consisted of a complex and expensive clutch-drive mechanism. It would therefore be advantageous to employ a device to perform these functions which is inexpensive to manufacture and quickly adaptable to manual charging, motor-driven charging, or both.